The new poinsettia cultivar, `603`, originated as an induced self-branching sport of a seedling known as `H-62` (not patented) in my greenhouse in Encinitas, Calif. It was selected because of its dark, rich red flower bracts, dark green foliage, self branching characteristics, and upright growth habit; traits that distinguish it from other poinsettia cultivars, and seem to make it a desirable plant for commercial greenhouse production. After selection, `603` was vegetatively reproduced from stem cuttings for test purposes in Encinitas, Calif. `H-62` is a proprietary plant and there are no specimens in the public domain. Poinsettia `H-62` is not self-branching in that no axillary branches develop as long as the apical bud is not removed (pinched). `603` is self-branching in that during development axillary branches elongate without removal of the apical bud. Under short day conditions, the axillary branches will develop flowers.
Poinsettia `603` most closely resembles poinsettia `409` (U.S. Plant Pat. No. 7,825), but differs in these aspects: `603` has a more compact and upright growth habit and fewer cyathia than `490` under the same cultural conditions. By subjecting clones of this plant to successive generations of vegetative propagation, it was demonstrated that the distinctive characteristics of `603` held true from generation to generation.